/Engine/Source/Editor/UnrealEd/Public/MouseDeltaTracker.h
Converts the delta movement to drag/rotation/scale based on the viewport type or widget axis
void ConvertMovementDeltaToDragRot ( [FSceneView](API\Runtime\Engine\FSceneView) * InView, [FEditorViewportClient](API\Editor\UnrealEd\FEditorViewportClient) * InViewportClient, FVector & InDragDelta, FVector & OutDrag, FRotator & OutRotation, FVector & OutScale ) const